From the leaves of Melaleuca quinquenervia (Clav.) S. T. Blake, the new flavonoid 5,7,3',4'-tetrahydroxyflavone 2'-O-beta-D-glucopyranuronide, as well as eight known flavonol glycosides have been isolated and characterized. The structures were established by chromatography, chemical degradation and UV spectroscopy and confirmed by ESI-MS and NMR spectroscopy. This is the first report on the isolation and identification of these flavonoids in the genus Melaleuca.